This is a Phase III study to evaluate the drug atosiban (brand name Antocin) for the treatment of preterm labor. Antocin is an inhibitor of the hormone oxytocin which has previously been shown to inhibit uterine contractions in animals. This is a placebo-controlled trial to demonstrate the efficacy of Antocin in preventing preterm delivery & the adverse fetal sequelae associated with preterm delivery Women in premature labor, with documented change on cervical examination between 20 & 34 weeks of gestational age will be considered candidates for the study.